1. Field of the Invention
This invention relates to a DQPSK mapping circuit for generating DQPSK signals from input data.
2. Description of the Prior Art
A DQPSK mapping circuit for generating DQPSK signals from input data is known. Japanese patent application provisional publication No. 6-252961 discloses a .pi./4 shift QPSK mapping circuit. Moreover, Japanese utility model application provisional publication No. 5-78050 discloses a .pi./4 DQPSK encoder.